In order to calculate the rate of change, we must subtract his end position and end time by the starting position and starting time. We are using the -15 feet since it is below the surface area as the starting position and the 10 seconds as the starting time. We make each of these into a fraction and subtract like so...
rate of change
rate of change
= rate of change
Therefore, we can see that the rate of change of the diver is or simplified would be
To convert gallons to pints, multiply the gallons by 8. Since there are 4 quarts in a gallon and 2 pints in each quart, you multiply by 8 since 4*2 is 8.